KVM: SVM: Remove VM from the GA Log notifier list before VM destruction

When a VM is being destroyed, delete it from the list used to process GA
Log interrupts before vCPUs are freed, otherwise avic_ga_log_notifier()
could theoretically hit a use-after-free if a GA Log notification arrives
for a vCPU after the last reference to the VM has been put.

Note, in practice, it's likely all but impossible to trigger UAF, as all
all irqfds and thus all IRTEs are cleaned up by:

  kvm_irqfd_release()
  |
  |-> irqfd_deactivate()
      |
      |-> irqfd_shutdown()
          |
          |-> irq_bypass_unregister_consumer()

And kvm_irqfd_release() is guaranteed to run before the last reference to
the VM is put.  KVM also configures GA Log interrupts only when a vCPU is
blocking (older versions of KVM configre GA Log interrupts at all times,
but AVIC is off by default on those kernels).  Hitting UAF would require
tearing down a VM shortly after a vCPU stopped blocking, and with a very,
very delayed IRQ from hardware.

Opportunistically use guard() to avoid a local "flags" variable.

Fixes: 5881f73757cc ("svm: Introduce AMD IOMMU avic_ga_log_notifier")
Cc: Naveen N Rao (AMD) <naveen@kernel.org>
Cc: Xiao Wu <xiaowu.417@qq.com>
Reviewed-by: Naveen N Rao (AMD) <naveen@kernel.org>
Link: https://patch.msgid.link/20260630210156.457151-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

0 files changed, 0 insertions, 0 deletions